#include<stdbool.h>

const char *bool_to_word (int value)
{
  return (value)?"Yes":"No";
}

#include <stdlib.h>
#include <string.h>

char *reverse_string(const char *word) {
    if (!word) return NULL;
  
    int len = strlen(word);
    char *res = malloc(len + 1);

    for (int i = len ; i >= 0 ; res[i] = word[len - (--i) - 1]);

    res[strlen(word)] = '\0';
    return res;
}

#include <stdlib.h>
#include <string.h>

char *reverse_string(const char *word)
{
    if (!word)
        return NULL;
    
    char *res = malloc(strlen(word) + 1);
    for(int i = strlen(word) ; i>=0 ; res[i] = word[strlen(word) - (--i) - 1]);
    
    res[strlen(word)] = '\0';
    return res;
}

#include <stdlib.h>
#include <string.h>

char *reverse_string(const char *word)
{
    if (!word)
        return NULL;

    char *res = malloc(strlen(word) + 1);
    int i = strlen(word);
    while (res[i] = word[strlen(word) - (--i) - 1])
        ;
    res[strlen(word)] = '\0';
    return res;
}